By finding out such parameters, it is possible to assess contact wear and to verity that the circuit-breaker is operating properly. Such monitoring of the state of the circuit-breaker enables maintenance to be planned and operating faults to be avoided.
The invention is based on the use of fluorescent fibers. In French Patent No. 2,640,386, the Applicant shows that it is possible to use fluorescent optical fibers to detect discharge light, whether visible or not, in equipment enclosed in a metal case.
Document JP-A-02 181668 shows how a looped fiber inside an enclosure may be used to detect the appearance of an arc due to a fault. A drawback of that described apparatus is that the fiber is immediately destroyed when the first fault appears. This is unimportant in the case of an electrical enclosure which, in any event, must be repaired after the fault, but that teaching cannot be used to detect the appearance of an arc in the interrupting chamber of a circuit-breaker that is required to operate hundreds of times over.
An object of the invention is to implement optical fiber arc-detecting apparatus which does not require the fiber to be replaced every time an arc appears.